1. Field of the Invention
In one of its aspects, the present invention relates to a foam element having at least one channel disposed therein, particularly useful in production of a climate-control vehicular seat (or element thereof). In another of its aspects, the present invention relates to a process for production of such a foam element. In yet another of its aspects, the present invention relates to a mold particularly adapted for production of the foam element.
2. Description of the Prior Art
Isocyanate-based polymers are known in the art. Generally, those of skill in the art understand isocyanate-based polymers to be polyurethanes, polyureas, polyisocyanurates and mixtures thereof.
It is also known in the art to produce foamed isocyanate-based polymers. Indeed, one of the advantages of isocyanate-based polymers compared to other polymer systems is that polymerization and foaming can occur in situ. This results in the ability to mould the polymer while it is forming and expanding.
One of the conventional ways to produce a polyurethane foam is known as the “one-shot” technique. In this technique, the isocyanate, a suitable polyol, a catalyst, water (which acts as a reactive “blowing” agent and can optionally be supplemented with one or more physical blowing agents) and other additives are mixed together at once using, for example, impingement mixing (e.g. high pressure). Generally, if one were to produce a polyurea, the polyol would be replaced with a suitable polyamine. A polyisocyanurate may result from cyclotrimerization of the isocyanate component. Urethane modified polyureas or polyisocyanurates are known in the art. In either scenario, the reactants would be intimately mixed very quickly using a suitable mixing technique.
Another technique for producing foamed isocyanate-based polymers is known as the “prepolymer” technique. In this technique, a prepolymer is produced by reacting polyol and isocyanate (in the case of a polyurethane) in an inert atmosphere to form a liquid polymer terminated with reactive groups (e.g. isocyanates). To produce the foamed polymer, the prepolymer is thoroughly mixed with a lower molecular weight polyol (in the case of producing a polyurethane) or a polyamine (in the case of producing a modified polyurea) in the presence of a curing agent and other additives, as needed.
As is known in the art, foamed isocyanate-based polymers are commonly used to produce parts used in vehicles. These include seats and various trim components.
In the production of a seat, particularly one for use in an automobile, it is known in the art to incorporate heating elements in the seat which are then connected to a power supply and a control system to allow the occupant of the automobile to turn on or turn off the heating elements for occupant convenience in colder climates. In the past, this has been achieved by molding into the seating element some form of resistant heating system.
This prior art approach is disadvantageous for a number of reasons.
First, since the heat provided from such a system is somewhat localized, it must be used over substantially the entire surface of the seat which, in many cases, has a deleterious affect on the comfort properties of the seat.
Second, since the heating system is resistive, there is a risk that some of the heat emitted will penetrate the seat rather than emit the seat toward the occupant. This can lead to premature discolouration and wear of the seat component and, in certain circumstances, may present a safety risk. Alternatively, an intermediate projective layer between the heating element and the seat pad could be used, but this adds extra expense and weight to the seat.
Third, the prior system simply provides a heated seat which is of little use to an occupant who seeks improved convenience in a warmer climate.
In light of the foregoing, it would be desirable to have a foam element which could be used in a vehicular seat to provide the ability to cool or heat the occupant in the seat. It would be advantageous if this foam element could be made in a relatively simple manner without the requirement for significant extra capital cost in the foam manufacturing plant.